At least four people were killed and 15 injured as a strong earthquake rocked the southern Philippines early today, destroying buildings and cutting off electricity, officials said.

At least four people were killed and 15 injured as a strong earthquake rocked the southern Philippines early today, destroying buildings and cutting off electricity, officials said.

Army spokesman Major Julieto Ando said heavy debris crushed two people in the southern town of Lake Cebu while falling construction blocks in nearby Sarangani province killed two others.

At least 15 people were treated for cuts and bruises at hospitals across the region, police said.

The earthquake, with a preliminary magnitude of 6.8, struck around 5:15am and was centred 10 miles under the sea, 150 miles southwest of the town of General Santos, said government seismologist Mylene Carlos.

In addition to the deaths caused directly by the earthquake, police said two people